In June 1982, Israel invaded Lebanon on a massive scale. The three most important reasons driving Israel's decision involved its basic conventions of national security, the perception that future confrontation with the PLO in Lebanon was inevitable, and the personal composition of the pinnacle of the defense establishment during the second Likud government. On the one hand, the political alternative to using military power – negotiations with the PLO over the resolution of the Israeli-Palestinian conflict – was rejected a priori by both the right-wing government of Israel, its main opposition party, Labor, and most of the leaders of the various PLO factions. On the other hand, the two main strategic alternatives to a deep invasion – continuation of the ceasefire in the theater of operations and the maintenance policy that combined measured retaliations and limited operations – were rejected as insufficient by the central leadership of the Israeli defense establishment. This last point was critical. While Israeli leaders up until 1981 preferred to exercise restraint and treat the PLO threat from Lebanon as a maintenance problem, once Sharon became Defense Minister, the probability that Israel would chose a ‘once and for all’ strategy against the PLO presence in Lebanon dramatically increased. In that respect, the June 1982 invasion was predetermined, though its exact date was left for the “next” random yet certain Middle East spark – in this case, the May 31, 1982, attempt to assassinate Shlomo Argov, Israel's ambassador to the United Kingdom.